1. Field of the Invention
The present invention relates to a motor having two degrees of free motion, and particularly, to a motor having two degrees of free motion which is able to generate a linear driving force and a rotational driving force simultaneously and respectively.
2. Description of the Background Art
A motor used as a driving power source of a mechanical system is an apparatus which converts electrical energy into kinetic energy, and includes a stator and an armature. The armature of the motor is moved when electric current is applied to the motor and generates an output mechanical force.
Motors are divided into two types, that is, a rotary driving motor generating a rotational driving force and a linear motor generating a linear driving force.
FIG. 1 is a cross-sectional view showing a conventional BLDC (Brushless Direct Current) rotary motor, that is, a rotary motor generating a rotational driving force. As shown therein, the rotary motor includes a stator 2 fixed in a motor case 1 formed with a certain shape, typically cylindrical, and a rotor 3 positioned inside the stator so as to be rotatable relative thereto. The stator 2 is formed such that a coil C1 is wound on a plurality of teeth or poles(not shown) formed on a laminated core formed by laminating a plurality of iron plates. And the rotor 3 is formed with one or more permanent magnets M1 inserted into an interior part of a cylinder. In addition, a driving shaft 4 is press-fitted into the rotor 3.
The rotary motor is operated as follows. That is, when an electric current is supplied to the coil winding C1 in the stator 2, the rotor 3 is rotated by an interaction of the magnetic flux generated by the electric current in the coil winding C1 and a magnetic flux of the permanent magnet M1 of the rotor.
FIG. 2 is a cross-sectional view showing a conventional fixed coil type linear motor generating a linear driving force. As shown therein, the linear motor includes a stator 13 including an outer core 11 fixedly coupled to a motor case 10 of a certain shape, and an inner core 12 fixedly coupled inside the outer core 11 with a certain gap therebetween, and an armature 14 inserted between the outer core 11 and the inner core 12. The outer core 11 and the inner core 12 are formed as laminated bodies, and a coil C2 is wound thereon. The armature 14 is made by coupling a plurality of permanent magnets M2 on a magnet holder 15 of a cylindrical shape.
The linear motor is operated as follows. That is, when an electric current is applied to the coil winding C2, the armature 14 is linearly moved by an interaction between the magnetic flux generated by the electric current flowing in the coil winding C2 and the permanent magnet M2.
However, an additional motion translation device such as a rack or a pinion must be installed in case that a linear driving force is needed when the rotary motor is used, and similarly, an additional motion translation device should be installed, if rotating force is needed when using a linear motor. Especially, if a rotational driving force and a linear driving force are both needed, then a rotary motor and a linear motor should both be used at the same time.
Therefore, an object of the present invention is to provide a motor having two degrees of free motion which is able to generate a linear driving force and a rotational driving force, respectively, and also is able to generate a linear driving force and a rotational force at the same time.
To achieve the object of the present invention, as embodied and broadly described herein, there is provided a motor having two degrees of free motion which includes a motor casing; a combined core having a first winding unit and a second winding unit and fixedly coupled inside the motor casing; a first coil winding wound on the first winding unit of the combined core; a second coil winding wound on the second winding unit of the combined core; a rotary armature having a permanent magnet inside and rotatably provided inside the combined core; a linear armature disposed laterally of the second coil winding and linearly movable relative thereto; an elastic means urging the linear armature away from the combined core; and a driving shaft coupled to the rotating armature as penetrating the rotating armature and coupled to the linear armature as penetrating the linear armature and respectively rotatably and linearly movable thereby.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.